超晶格Al_xGa_（1－x）As／GaAs中相对键强度的研究

Investigation of Relative Bond Strength in Al_xGa_(1-x)As/GaAs Superlattices

用半经验的ＣＮＤＯ／２量子化学计算方法，对一组模拟超晶格ＡｌｘＧａ１－ｘＡｓ／ＧａＡｓ的原子簇体系作了第一性原理的电子结构研究。结果表明，化学键Ａｌ—Ａｓ和Ｇａ—Ａｓ的强度，在ＡｌｘＧａ１－ｘＡｓ环境中的结果均高于它们在纯晶体ＡｌＡｓ和ＧａＡｓ环境中的数值；随着ＡｌｘＧａ１－ｘＡｓ中Ｘ值的增大，Ｇａ－Ａｓ键强度相应地提高，但平均键强度计算结果，Ｇａ－Ａｓ总低于同环境中的Ａｌ－Ａｓ。本文结果同ＡｌｘＧａ１－ｘＡｓ／ＧａＡｓ红外光谱键强度分析等实验事实相吻合，而且为离子注入ＡｌｘＧａ１－ｘＡｓ／ＧａＡｓ中引起的晶格损伤分布行为提供了合理的解释。

The electronic structures of a group of atomic cluster systems used to simulate AIxGa1-xAs/GaAs superlattices are investigated on first-principles study using CNDO/2 which is a semiempirical method in quantum chemistry computation. The results show that the strength of chemical bonds Al-As and Ga-As in environment AlxGa1-x As are greater than those in pure crystals AlAs and GaAs ,and the strength of Ga-As increases with increasing x value in AlxGa1-xAs,but the average strength of Ga-As is always smaller than that of Al-As in same environment.These results are in agreement with the bond strength analysis of infrared reflection spectra of AlxGa1-xAs and can explain the distribution of lattice damage created in ion-implanted AlxGa1-xAs/GaAs superlattices.